7 Swamp coolers are very effective air conditioners in semia

7. ‘Swamp coolers’ are very effective air conditioners in semi-arid places like West Texas. They work by flowing water over porous pads and blowing air through those pads into the room. What physics principle allows these units to be effective?.

Solution

the principle here involved is joul - kelvin expansion,

according to this effect,when air passes slowly through porous plug from a constant high pressure to constant low pressure ,it shows temperature change.

before passing through porous plug ,if the temoerature of gas is less than its critical temperature it shows fall in temperature as work done by the gas is more than work done on gas.

    this phenomenon is used in swamp coolers